Alec Baldwin has reprised in his role as Donald Trump for the latest episode of Saturday Night Live’s Weekend Update, identifying the US president as the true martyr of the tragic Charlottesville rally.

A 12-year-old singing ventriloquist has been awarded US$1 (A$1.3) million prize and her own Las Vegas show after taking the America's Got Talent crown on the season 12 finale of the NBC reality competition.

But her most devastating blows were landed when speaking about her stamina, his past statements on women and his connection to the birther conspiracy theory.

Racism accusations

An hour into the debate, Clinton landed a powerful broadside on Trump for his position on birtherism.

"He tried to put the whole racist birther lie to bed, but it can't be dismissed that easily," Clinton said.

"Donald started his career back in 1973 being sued by the Justice Department for racist discrimination because he would not rent apartments to African-Americans.

"He actually was sued twice, so he has a long record of engaging in racist behaviour.

"And the birther lie was a very hurtful lie."

Trump defended his past history with African-Americans, arguing he had settled those Justice Department lawsuits "with zero admission of guilt".

Stamina and look

When Trump was asked to explain his description of Clinton not having the "presidential look" earlier this month, he said he was referring to Clinton's stamina.

"I don't believe she does have the stamina," he said.

"To be president of this country you need tremendous stamina."

But Clinton's reply shut the suggestion down.

"As soon as he travels to 112 countries, negotiates a cease-fire, a release of dissidents or even spends 11 hours testifying in front of a congressional committee, he can talk to me about stamina," Clinton said.

She then pivoted back to criticise Trump for trying to switch from looks to stamina.

"This is a man who has called women pigs, slobs and dogs. And someone who has said pregnancy is an inconvenience to employers," she said.

"Who has said women don't deserve equal pay unless they do as good a job as men."

ISIS claims

Trump went on to make a bizarre gaffe about Islamic State, at first criticising her for putting her plan to fight ISIS on her website for everyone to see.

Such a claim would have required Clinton to have been fighting Islamic State since 1966, though the group first proclaimed its caliphate in 2014.

Saying too much

But Trump also slipped into his bad habit of bragging about his business successes.

Midway through the debate he made the odd decision to spruik his recently opened hotel in Washington DC, something he had also done last week during a press conference about the birth certificate conspiracy theory.

And when Clinton suggested he was hiding dodgy tax practices by not releasing his tax return, Trump did not deny it.

"That's called business," he replied.

And when Trump bragged about having the temperament to be president, he probably was not expecting the crowd to laugh at him.

The aftermath

In a post-debate interview broadcast on CNN, Trump said he might bring up Bill Clinton's infidelity in the next debate.

"I'm very happy I was able to hold back on the indiscretions with respect to Bill Clinton, because I have a lot of respect for Chelsea Clinton," he said.

Chelsea Clinton was sitting in the front row during today's debate at Hofstra University, New York.

Trump had earlier extended an invitation to Bill Clinton's former mistress Gennifer Flowers to attend the debate as one of his guests.

He later rescinded the invitation after she accepted.

Will it change votes?

This is a campaign with unusually high numbers of undecided voters, but in spite of Clinton coming out ahead, she did not land the knockout blow on Trump.

However, Democrats will likely be happy with Clinton's performance, and Republicans will be unhappy with Trump's.